1. Field of the Invention
The present invention relates to a moving amount estimating method for estimating a moving amount of a movable mobile body capable of being moved by rotation of a wheel, a moving amount estimating apparatus, and an autonomous mobile body including the moving amount estimating apparatus.
2. Description of the Related Art
Conventionally, a mobile body that can be moved in a predetermined space by rotation of a wheel is known. A travelling distance and/or a current position of such a mobile body are estimated based on a rotating amount of a wheel and/or a distance between the mobile body and an object present around the mobile body.
For example, JP 2004-318721 A discloses an autonomous travelling vehicle that includes an encoder and a distance measuring sensor and can travel according to rotational drive of a travelling wheel. In the autonomous travelling vehicle, a travelling distance of the autonomous travelling vehicle is calculated based on a rotation number measured by the encoder, and a distance between the autonomous travelling vehicle and a wall or an obstacle present around the vehicle is measured by the distance measuring sensor.
Further, the autonomous travelling vehicle described in JP 2004-318721 A compensates for a travelling distance per predetermined time calculated based on the rotation number of the travelling wheel using a change amount in the distance between the autonomous travelling vehicle and the wall or the obstacle measured by the distance measuring sensor per predetermined time. That is, in the conventional autonomous travelling vehicle, when the travelling distance calculated based on the rotation number of the travelling wheel includes an error caused by slippage between the travelling wheel and a floor, the error is compensated for according to the change amount of the distance per predetermined time measured by the distance measuring sensor.
However, the measurement error is not only included in the travelling distance calculated based on the rotation number (rotating amount) of the wheel measured by the encoder but also included in the distance between the autonomous travelling vehicle and an object such as an obstacle measured by the distance measuring sensor. For this reason, when a moving amount of the autonomous mobile body is small, the accuracy of the latter calculated travelling distance is below the accuracy of the former calculated travelling distance. In the autonomous travelling vehicle of JP 2004-318721 A, when an error is included in the distance measured by the distance measuring sensor and the moving amount of the autonomous mobile body is small, the travelling distance is transcribed into the travelling distance having lower accuracy.